Alien and invasive scale insect species in Poland and their threat to native plants.

A complete list of scale insect species (Coccoidea) alien to Poland is presented for the first time. A total of 51 species have been introduced to Poland since the 19 th century, mainly from the Neotropical and Oriental regions. Of this group, 46 species live only indoors, 4 species develop outdoors and 1 species Pulvinaria floccifera (Westwood) develops both indoors and outdoors. Among the scale insects introduced into Poland, 16 species are considered to be invasive, while 13 species pose the greatest threats to native plants. For each species, the date of the first record in Poland, their origin, category and period of introduction, environment and principal hosts in Poland, invasive status and threat to native plants are provided based on bibliographic sources.